The production of asphalt shingles of various colors is well known. Generally, such shingles are colored by applying a mixture of colored granules to a moving, asphalt covered sheet. The application of the granules is made from a series of granule containers by means of feed rolls. The length and spacing of each mixture on the sheet is known as a "drop" and is dependent on the speed of the feed roll, the relative speed of the sheet and the length of time during which the drop is made.
In normal granule application, a fixed blend cycle is employed. Such a cycle is repetitive and can be altered only with difficulty. As a result, there frequently results an undesirable "patterning" on the roof upon application to the surface on which the shingles are laid. Under certain application conditions varying with the cycle length, the drops are visible on the laid shingles as bands or stripes on the roof. The longer the cycle or the less contrast between drops in the blend, the less apparent the patterning will be, but it is almost always present.
The apparatus of this invention is directed to the solution of that problem.